Bird Identification: CLOSED: wonder what kind of birds these could be..

Some days ago I photographed these quite large birds in a protected nature area, where lots of migrating birds from colder climates overwinter. Its an area that gets flooded during that period, so also lots of migrating water birds..
These ones I was lucky to observe for a long time as they flocked together in two large trees.

Thank you pelletory and Resin!
Could it not be Phalacrocorax pygmeus ? They were large but not as large as Phalacrocorax aristoteles which is 75cm. They also don't have that tuft on top of their heads.
But they should at least belong to the genus Phalacrocorax, as I've just read in a book where they describe that typical behaviour of standing with spread wings.

Resin, in that book they also say that Phalacrocorax pygmeus, (not like the other species which are indeed strictly marine), I translate :
"habitat; Lakes, pools, slow rivers, marshes and dense woodlands with open sweet watersurfaces. Some overwinter in salt marches..
...they gather together cosily in large trees drying their wings."...
So that also answered my question about that strange habit of standing there with open wings exposing themselves to the elements.. brrrr...

Well, I didn't manage to get a reasonable quality in a cropped version of mine. The trees were far off and very tall and my tele lens is not that powerful and my hands were shaking from the cold...
But I give it here anyway..

Phalacrocorax pygmeus is much smaller, only the size of a small duck, with a short, stubby bill and a long tail. You would also have to go to the Danube Delta (Romania) to see that many of them! (if I remember rightly, there is a single record for the Netherlands, which is the only one ever seen in northwestern Europe)